737 Flight Controls - Roll & Speedbrakes

This video is the first in of a 3-part series on Boeing 737 Flight Controls. This one covers roll control and also speedbrakes.
Contents:
0:00 Intro
0:43 Ailerons
3:07 Flight Spoilers & Speedbrakes
14:38 Ground Spoilers
18:03 Aileron - Spoiler Mechanics
56:43 Jams etc
58:37 Aileron - Spoiler Interaction
1:10:15 MAX Fly-By-Wire Spoilers

[@Trebuchet48]

Hi Chris. I just discovered your channel yesterday because KZbin suggested the excellent plug door one. Then I had to watch this one because I'm a retired Boeing Flight Controls lead engineer who at one point in my 20+ year career held design responsibility for this system. I was never as familiar with it as I wanted to be as I had many other responsibilities as well so I'm very much enjoying the video, bringing back memories and learning a few things along the way. Great job!

[@ChrisBrady737]

Thanks for your kind comments. Great to hear that the videos are bringing back some memories for you.

[@Trebuchet48]

And now that I've finally finished the video, a couple of comments: 1. That spoiler mixer mechanism is truly a marvel. I've been in awe for years of the guys who came up with it. It's basically a mechanical analog computer. The 747, other than -8, has two of them! 2. Some additional discussion of the autospeedbrake system would have been nice. 3. Now I've got to watch all the other systems!

[@jeffberner8206]

As a recent retiree from Boeing, I'd like to add a comment or two. The 737 Classic aileron operates 20-degrees trailing edge up and 20-degrees trailing edge down. The 737NG aileron operates 20-degrees trailing edge up and 15-degrees trailing edge down. This bias was introduced on the 737NG due to the revised airfoil shape which increased the pressures on the aft part of the wing. Costly changes to the actuation system would have been required to provide the additional downward travel on the Classic. The aileron is rigged downward on the ground so that it will be faired at cruise altitudes to minimize drag in-flight. The same can be said for flaps.

[@ChrisBrady737]

Hi Jeff, thanks for the fascinating insight. It is great to hear the background to design changes.

[@Jet-Pack]

Fantastic presentation especially with the real world videos from inside the wheel well and seeing the parts move.

[@ChrisBrady737]

Thank you. I agree the “real world” videos are best but unfortunately not all subjects lend themselves to this treatment. Hydraulics, flight controls and landing gear are all on display in the wheel well but not other subjects.

[@luukbeers777]

Gonna start my MCC course (B737 FSTD) next week and with your videos I’m gonna rock it. Thanks a lot Chris, it’s really helpful!

[@ChrisBrady737]

That's great to hear. Good luck with your course.

[@737simguide2]

Thanks Chris! As always, excellent info and thanks for your hard work producing and sharing.

[@ChrisBrady737]

Thanks for your kind words, glad you enjoyed it

[@adimo6673]

Fantastic information! One hour and a quarter of heaven for an airplane geek like me. Thank you for posting this video. Also thank you for writing the book!

[@ChrisBrady737]

My pleasure, thanks for your kind words.

[@benkenobi2139]

Cheers Chris! Love your explanations. With your videos I think I will nail the technical exam for my 737 TR. Thank you so much mate!

[@ChrisBrady737]

Glad to help. Best of luck!

[@aviationengineering]

Great work , keep it up Chris 👏🏻

[@ChrisBrady737]

Thank you, glad you enjoy them.

[@MikeOBrien0]

Awesome vid, thx again for publishing these! On a side note I can't believe how pristine the forward bay is on the pictured aircraft, gorgeous. Normally you encounter a thick layer of dust and grime.... Nice to see whats underneath that. ;)

[@ChrisBrady737]

It certainly is a well looked after aircraft

[@larrydockery7201]

love your vids chris keep them coming

[@ChrisBrady737]

Thanks Larry, I should have another one out within a week or two.

[@telescope64]

Fantastic explanation.The video brought the complex subject to life.Very thorough,thanks very much Chris. Best wishes from Paul.

[@ChrisBrady737]

Thank you Paul, and thank you once again for your help

[@shahidsharif]

Amazing video, really great to see the components moving in the wheel well bay, it is really enhancing my recurrent system studies.

[@ChrisBrady737]

My pleasure, thanks for watching.

[@ElfoRomagnolo]

Every video deserve a like and a comment: thanks a lot for the great work, that’s what learning is all about 👏👏👏

[@ChrisBrady737]

My pleasure, thank you for your support.

[@joseteixeira5900]

Good info, I've been close to finish my 737 type course, and surely helps a lot. Even the tutor used some of these videos to the classroom. Great job Mr Chris. And long life the 737

[@ChrisBrady737]

Thank you for your kind comments. Good luck with your type rating!

[@joseteixeira5900]

@@ChrisBrady737 Thank you Sir. Mid December will make the exams for B1 and B2 maintenance engineering.

[@DL14204]

Great video. Shared to colleagues.👍

[@ChrisBrady737]

Awesome, thank you!

[@mortimerduke3645]

Really insightful and very informational video! Thank you!

[@ChrisBrady737]

Glad to hear that you found it interesting. thanks for watching.

[@seanrazali]

Thank you So much. Will be flying the MAX soon.

[@ChrisBrady737]

My pleasure. Enjoy the MAX !

[@gabers99]

Excellent video. I could have done with all these during my type rating a couple of years ago.

[@ChrisBrady737]

Glad it was helpful, tell your colleagues!

[@theacousticsound9376]

Thank you for making this very informative video! I'm currently taking my 737NG type course and this helped me understand the flow of everything a bit better from the demonstrations you provided. One thing that you missed, is the Ground Spoiler Interlock Valve, which is opened or closed from a Teleflex cable directly connected to the R/H MLG. This valve is what allows hydraulics to operate the Ground Spoilers only on ground. The Spoiler Ratio Changer always gives an input to the Ground Spoiler Control Valve.

[@ChrisBrady737]

You are correct but there is a limit to how much detail I can go into in these videos. Thanks for the feedback.

[@marie-benedicteclaudel3624]

this is so interesting, helped me so much for my 737 TR, big thank you !

[@ChrisBrady737]

You are very welcome. Have you considered getting the book? It will help you a lot with your TR.

[@bigmakskartoshechkoy6210]

Thanks a lot! Great video! Tremendously interesting!!

[@ChrisBrady737]

Glad you enjoyed it!

[@MenezesLouis]

Thanks for the wonderful explanation

[@ChrisBrady737]

You are very welcome

[@umi3017]

Thanks Chris, I just want add some my experience on the speed brake lever, it's the position marker... On 737, weirdly, the position marker on the speedbrake lever is the little triangle on the back facade of the lever, rather than the much obvious little tab on the right. I have seen quite some trainee on simulator put that tab on ARM mark to get the SPEEDBARKE EXTENDED light on approach, or pull it slightly over FLIGHT DETENTE... it just looks too instinctively correct, even if you have briefed them before flight....

[@ChrisBrady737]

Good point Umi

[@jakobrincke3490]

True hero of the internet😂😂. Amazons Werk man i was durchging for such an Channel for years

[@ChrisBrady737]

Glad you like it. Enjoy the other videos too!

[@Yura1603]

Thank you very much for your videos. Now I’m taking my cbt course for Boeing 737NG in Russia to get my new type rating, and your videos very helpful to understanding such a difficult systems of this great airplane. And I’m agree with you that information from fcom is not sufficient (enough) to understand it.

[@ChrisBrady737]

You are very welcome, thanks for watching and good luck with your type rating

[@medlevinger]

Amazing video, preparing the type rating with the old CBT trainer isn't half as efficent. Thanks very much.

[@ChrisBrady737]

You are welcome. I agree, traditional CBTs can be awful.

[@jmaerials5506]

Great review!! Would you be willing to add a section of common check ride questions to the end of your presentations? Keep up the great content.

[@ChrisBrady737]

Thanks, I will certainly consider it

[@johnhoss2950]

Excellent!

[@ChrisBrady737]

Thank you

[@balazsegressy3788]

Some additional info About the Landing Attitude modifier from our Maintenance Training book: SCE- Spoiler control electronics/ Spoiler computer The landing attitude modifier (LAM) system performs two functions. The first LAM function applies when the flaps are in the 15 or 25 unit position. This function uses the flight spoilers to help capture the glide slope. If the airplane is above the glide slope, the flight spoilers extend to decrease lift. If the airplane is below the glide slope, the flight spoilers retract to increase lift. The second LAM function applies when the flaps are in the 30 or 40 unit position. The LAM system uses the flight spoilers to help the noselanding gear clearance. The LAM system extends flight spoilers equally on approach. This will decrease lift and make the airplane use a higher angle of attack. The LAM function uses inputs from these systems to calculate the spoiler commands: − ADIRU L/R - supply the SCE with computed airspeed (CAS) − FCC A/B - supply the SCE with position of the flight controls − RA L/R - supply the SCE with the height of the airplane − SMYD 1/2 - supply the SCE with the position of the flaps and angle of attack (AOA) − Thrust resolver angle (TRA) (2) - provided to the SCE from the engine electronic controls (EECs) through the display processing computers (DPCs). The SCE stops the LAM function when any of these occur: − Airspeed is less than 60 kts − Airplane is below 100 ft − TRA for either engine is less than 70 degrees. The SCE tells these systems that the LAM function is active: − DFDAU − DPC.

[@ChrisBrady737]

Good to know, thank you

[@guilhermechaves5957]

Hello Captain. Great video!! I've one quick question. I was checking the Landing Gear Section of the MAX QRH (Landing Gear Lever Will Not Move Up After Takeoff) and there's no advisory regarding to the use of speedbrake in flight. Why is it different from the NG? Thanks a lot!

[@ChrisBrady737]

Hi Guilherme, Great to hear that you enjoyed the video. The MAX procedure is difference to all previous generations because the speedbrake system is FBW. Regards Chris

[@gunit5477]

So when the pilot lets go of the wheel, the wheel goes back to natural position? Same with rudder pedals and yoke?

[@eh3twenty]

I’m about to transition to the B737-8 MAX from the B787, and this video (and entire website) was an invaluable tool in understanding the myriad mechanical interconnectivities of the B737 flight control system - in particular, manual reversion. Thank you for sharing your vast knowledge with your colleagues worldwide! One question I have is, given the move to a fly-by-wire spoiler system and absence of the spoiler mixer and ratio changer on the MAX, how have they implemented the aileron transfer mechanism/aileron spring cartridge? Or have they left all the linkages in place just for this purpose?

[@ChrisBrady737]

Thank you for your kind comments about my videos and website, you may also find the book useful for your transition. Re your question, the aileron spring cartridge in the wheel well has gone as the aileron and spoiler systems are now effectively separate so a jam in one will not cause a jam in the other. The Aileron transfer mechanism at the control columns remains in case of a control column jam.

[@cameronmurphy7713]

Hi Chris! I can’t thank you enough for all you’re videos, they really are gold dust. Your book keeps me busy on the long(ish) trips down the canaries and back! Weird question if you don’t mind (I’m doubting whether there’s even an answer to this). I spend a lot of time in the jumpseat as safety pilot in my company, and after countless hours staring at the overhead panel I’ve noticed something which now keeps me awake at night. From what I can see, every guard for every switch has the tiny little pinhole in it for the locking wire, except two, the Flight Control Switches. Is there a reason for this? It seems strange that Boeing would manufacture/purchase different guards solely for these two switches. Many thanks! Cam (EMA based RYR FO)

[@hzgl]

Thanks captain Chris! That was a fascinating episode. On your website you mentioned a new feature of the MAX spoilers, the one curiously named "Elevator Jam Landing Assist". How do you like it in your test flights?

[@ChrisBrady737]

It is not a standard flight test item, like an aileron / spoiler jam is not a standard test item. But I have every confidence it would work as advertised.

[@hzgl]

@@ChrisBrady737 Thanks captain!

[@umi3017]

As I tried on LvD simulator, it feels quite weird. As I see on HUD, it almost have no effect on your pitch angle, but did quite some change on FPV... It did the job done to get you on the runway, but just feels quite odd in the process...

[@hzgl]

@@umi3017 Fascinating, thank you!

[@balazsegressy3788]

@@umi3017 Good feedback!! Some hands on experience!

[@logandenelskycfi]

How do the aileron cables get through the pressure vessel? Love the videos, Chris!

[@ChrisBrady737]

They are routed through sealed airtight units, same at the aft pressure bulkhead for the stab, elevator & rudder cables. Unfortunately I cant attach a photo here to show you one.

[@sebastianmatiasanzoategui4248]

Hello Chris, firs I’d like to congrats you for the videos, they are awesome, deeply information even much more than a CBT. I have like 2500 hours on the 737 and I love the plane. The other day a captain told me do not use the speed brakes above Flap 15. I’ve only saw the restrictions on the manuals of the company but no more info. Now I’ve seen yours videos and I saw your explanations related with the trim tabs on the elevator and Boeings bulletin and my question is, If after this bulletins the problem should be fixed in all the planes why the restrictions are still on the manuals? This was 20 year ago so I don’t get it clear. Thanks again, I use your videos for my assessments to review the systems. Thanks and please don’t stop doing it all the colleagues really appreciate it.

[@ChrisBrady737]

Hi Sabastian, Thank you for your kind comments about my videos, it is always good to hear they are being well received. The issue of using speedbrake with flap is covered in the FCTM as follows: "The use of speedbrakes with flaps extended should be avoided, if possible. With flaps 15 or greater, the speedbrakes should be retracted. If circumstances dictate the use of speedbrakes with flaps extended, high sink rates during the approach should be avoided. Speedbrakes should be retracted before reaching 1,000 feet AGL." As you can see the issue is around the high descent rate near the ground, not elevator tabs. Regards Chris

[@sebastianmatiasanzoategui4248]

@@ChrisBrady737 yes I understand that. A saw it on the FCTM AND FCOM. and the restriction below 1000 ft is out of doubt. The high rate of decent is also clear. I’ve just thought it was related also with the trim tabs. Thank you so much for you answer.

[@mohammedpilot2335]

Thanks

[@ChrisBrady737]

Welcome

[@bigmakskartoshechkoy6210]

Could you explain please, how do pilots identify the moment when they have to extend flaps before landing?

[@ChrisBrady737]

Flaps enable you to fly slower. So when you need to decelerate below the safe speed at which the wing can fly clean (around 200-230kts depending upon weight) then you extend flaps in stages and decelerate towards your landing speed.

[@bigmakskartoshechkoy6210]

@@ChrisBrady737 Thanks captain Chris!

[@balazsegressy3788]

The SPEEDBRAKES EXTENDED light shows when all these conditions occur: 1. • Airplane in the air • Speedbrake lever is more than 7.5 degrees • TE flaps are more than the 10 units or the altitude is less than 800 feet. These conditions occur if the pilot uses the speedbrake lever during the landing approach. 2. • Airplane on the ground • Ground spoiler interlock valve pressure switch measures more than 750 psi • Speedbrake lever is in the down position. These conditions occur if the ground spoiler actuators receive hydraulic power with the speedbrake lever in the down position. This is a failure condition.

[@ChrisBrady737]

Thanks again for the additional info

[@davecat1458]

Is aileron trim ever used, and if so under what circumstances?

[@ChrisBrady737]

Not very often, just to correct a crooked aircraft.

[@jeoffreydullaert743]

Small question - do the flight spoilers still extend symmetrically when using speedbrakes during a turn with more than 10° bank angle?

[@ChrisBrady737]

They deploy asymmetrically during a turn, see Aileron / Spoiler Interaction section of the video.

[@jeoffreydullaert743]

@@ChrisBrady737 I know they do during a regular turn, but does it also apply when speedbrakes are extended (and thus flight spoilers already in the fully extended position)? Do the flight spoilers on the upgoing wing retract (partially)?

[@banty186]

Many many Thanks you for presentation.

[@ChrisBrady737]

My pleasure, glad you found it useful

[@scottb721]

Fly by Wireless 🤣🤣 That'll be next !! 😁